Yu's family had been Dolists since around 1800 PD. He was able to leave the prole housing complex and the Basic Living Stipend behind when he entered People's Navy Academy. Not many non-Legislaturalists were able to become officers in the PN, but Yu was able to fight his away in, working his way through the ranks by merit, which was a rarity in the People's Republic era. During his time at the academy, he was almost caught with history tapes from the Pre-People's Republic era, which were illegal at the time. He considered it one of the most terrifying events in his life.

Captain Yu was able to pick some of the more senior officers for Operation Jericho. He chose officers who displayed nearly the same qualities that he saw in himself.

During his assignment, Yu respected the rank of Sword of the FaithfulMatthew Simonds, the Masadan liaison. He warned Simonds that the time to proceed with Operation Jericho was now, especially when Manticore and Grayson formalized their alliance. Yu did not agree on how his new superiors liked to keep their junior officers waiting to exercise their authority. He was confident that could handle any ship of the Royal Manticoran Navy, whether a destroyer or a heavy cruiser. Personally, he did not like covert operations, and believed that some higher officer had underestimated the Masadans, or lied to him.

During the First Battle of Yeltsin's Star, Yu was at the CIC on Thunder of God. During the battle, he got frustrated with the Masadans because they would not use the Havenite vessels to their full potential[2]. He gave the advice that AdmiralErnst Franks should bypass HMS Madrigal and go after the Grayson survivors, but Sword Simonds refused, which led to severe Masadan losses during Madrigal's last stand.

After the battle, Yu argued for the invasion of Grayson, but it was decided to suspended it because of the battle losses. Simonds accused Yu of overstating Thunder of God's capabilities. Thunder and Principality spent their time shuttling Masadan LACs through hyper to reinforce Blackbird Base.[3] (HH2ch.17)

At the time of the Battle of Blackbird, Captain Yu and Thunder of God were forty hours overdue. Afterward, Yu informed Ambassador Lacy about the defeat at Blackbird. They decided to cease offensive operations and revert Thunder of God to PNS Saladin, hoping that the threat of outright war with Haven would deter a Manticoran reprisal against Masada long enough for a diplomatic resolution. Unbeknowst to the Havenites, their conversation was recorded by Deacon Sands, and the Council plotted to seize Thunder for themselves. (HH2ch.27)

The Masadans ordered the use of Thunder of God to transport soldiers to the orbital forts in the Endicott System, a ruse to allow them to take the ship. In the time before the mutiny, Yu was puzzled by the relative silence from the Council and Sword Simonds. However, he then received Commander Manning's message about the Masadan's plan to take over his ship; he ordered a Code: Bounty Four-One, which meant that the ship could not be retaken. He led his crew fighting to the ship's boat bay and on to the pinnaces to escape. Around 160 crew (about 27% of the ship's Havenite complement) were able to escape. (HH2ch.29,30)